Acesulfame potassium (ace-SUHL-faym), also known as acesulfame K (K is the symbol for potassium) or Ace K, is a calorie-free sugar substitute (artificial sweetener), and marketed under the trade names Sunett and Sweet One. In the European Union, it is known under the E number (additive code) E950.[1] It was discovered accidentally in 1967 by German chemist Karl Clauss at Hoechst AG (now Nutrinova).[2] In chemical structure, acesulfame potassium is the potassium salt of 6-methyl-1,2,3-oxathiazine-4(3H)-one 2,2-dioxide. It is a white crystalline powder with molecular formula C4H4KNO4S and a molecular weight of 201.24 g/mol.[3]

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Acesulfame K is 200 times sweeter than sucrose (common sugar), as sweet as aspartame, about 2/3 as sweet as saccharin, and 1/3 as sweet as sucralose. Like saccharin, it has a slightly bitter aftertaste, especially at high concentrations. Kraft Foods patented the use of sodium ferulate to mask acesulfame's aftertaste.[4] Acesulfame K is often blended with other sweeteners (usually sucralose or aspartame). These blends are reputed[by whom?] to give a more sucrose-like taste whereby each sweetener masks the other's aftertaste, or exhibits a synergistic effect by which the blend is sweeter than its components. Acesulfame potassium has a smaller particle size than sucrose, allowing for its mixtures with other sweeteners to be more uniform.[5]

Unlike aspartame, acesulfame K is stable under heat, even under moderately acidic or basic conditions, allowing it to be used as a food additive in baking, or in products that require a long shelf life. Although acesulfame potassium has a stable shelf life, it can eventually degrade to acetoacetamide, which is toxic in high doses.[6] In carbonated drinks, it is almost always used in conjunction with another sweetener, such as aspartame or sucralose. It is also used as a sweetener in protein shakes and pharmaceutical products,[7] especially chewable and liquid medications, where it can make the active ingredients more palatable. The acceptable daily intake of acesulfame potassium is listed as 15 mg/kg/day.[8]

Acesulfame potassium as well as other sugar substituents were intercalated into some layered double hydroxide (LDH) hosts by ion exchange. Characterization tests have shown that there is complete intercalation of the anions into the LDH hosts. In acesulfame K, the absorption at 1290 cm^-1 is found in the intercalated product at 1314 cm^-1.[9] Since this absorption corresponds to the S-O double bond, it means that the bonds interact strongly with the metal hydroxide layers thus an orientation of the intercalated molecules is possible.[9]

Acesulfame potassium is one of the non-nutritive sweeteners that aids patients with type 1 diabetes. It provides a super sweet taste without affecting glycaemic responses and without the high content of caloric sugars. Some studies, however, discovered that the consumption of non-nutritive sweeteners has led to weight gain thus increasing the risk of type 2 diabetes.[10]

Through a Maximal Electroshock Seizure test, non-nutritive sweeteners including acesulfame potassium were labeled as anticonvulsants.[11] This means that there is an association between the structure of the receptor that triggers the sweet sensation and the structure of the molecular targets of antiepileptic drugs.[11] It was also discovered that these non-nutritive sweeteners’ anticonvulsant activity is caused by modulation of brain mGlu.[11]

Other names for acesulfame K are potassium acesulfamate, potassium salt of 6-methyl-1,2,3-oxothiazin-4(3H)-one-2,3-dioxide, and potassium 6-methyl-1,2,3-oxathiazine-4(3H)-one-3-ate-2,2-dioxide.

Acesulfame potassium was developed after the accidental discovery of a similar compound (5,6-dimethyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide) in 1967 by Karl Clauss and Harald Jensen at Hoechst AG.[12][13] After accidentally dipping his fingers into the chemicals with which he was working, Clauss licked them to pick up a piece of paper.[14] Clauss is the inventor listed on a United States patent issued in 1975 to the assignee Hoechst Aktiengesellschaft for one process of manufacturing acesulfame potassium.[15] Subsequent research showed a number of compounds with the same basic ring structure had varying levels of sweetness. 6-methyl-1,2,3-oxathiazine-4(3H)-one 2,2-dioxide had particularly favourable taste characteristics and was relatively easy to synthesize, so it was singled out for further research, and received its generic name (acesulfame-K) from the World Health Organization in 1978.[12] Acesulfame potassium first received approval for table top use in the United States in 1988.[8]

As for potential negative effects, when injected directly in very large doses (the equivalent of 10 g for an average sized human male), acesulfame K has been shown to stimulate dose-dependent insulin secretion in rats, though no hyperglycemia was observed.[19]

One rodent study showed no increased incidence of tumors in response to administration of acesulfame K.[20] In this study, conducted by the National Toxicology Program, 60 rats were given acesulfame K for 40 weeks, making up as much as 3% of their total diet (which would be equivalent to a human consuming 1,343 12 oz cans of artificially sweetened soft drinks every day). No sign indicated these (or lower) levels of acesulfame K increased the rats' risk of cancer or other neoplasms. However, a similar study conducted with p53haploinsufficient mice showed signs of carcinogenicity in males but not females.[20] Further food safety research has been recommended.[16][21] Acesulfame K did not show any DNA-damaging properties.[22]

Research suggests acesulfame K may affect prenatal development. One study appeared to show acesulfame K is ingested by mice through their mothers' amniotic fluid or breast milk, and this influences the adult mouse's sweet preference.[23]

Additional research on the effects of acesulfame K on mice revealed chronic use over a period of 40 weeks resulted in a moderate but limited effect on neurometabolic function, and impaired cognitive memory functions. The authors proposed that this was caused by metabolically induced suppression of the T1r3 subunit of the taste receptor in the hippocampus.[24]

Environment Canada tested the water from the Grand River at 23 sites between its headwaters and where it dumps into Lake Erie. The results suggest the artificial sweetener acesulfame is the best at evading wastewater treatment, and it appears in far higher concentrations than saccharin or sucralose at the various test sites.[25]

In studies with animals, those animals who were exposed to low calorie sweeteners including acesulfame potassium have experienced some negative conditions including increased food consumption and weight gain, a greater percent of body fat, an increase in fasting glucose, a decrease in post-prandial thermogenesis, and a lower GLP-1 release during glucose tolerance testing.[26]